A Theoretical Assessment of PFAS VI Potential and Implications
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Geosyntec conducted a preliminary evaluation of PFAS compound volatility by calculating theoretical maximum vapor concentrations and theoretical dimensionless Henry"s Law Constants from reported vapor pressures and aqueous solubilities for several classes of PFAS compounds.

The compounds exhibit a wide range of vapor pressures (2E-04 to 1E+03 Pa), aqueous solubilities (1E-05 to 1E+04 g/L) and, consequently, a wide range of calculated vapor concentrations (5 to 2E+8 μg/m3) and theoretical dimensionless Henry"s Law Constants (1E-09 to greater than 1). The vapor pressure indicates the volatility of the compounds from pure-phase liquid or solid phase and the Henry"s Law Constants indicate the volatility of the compounds from the aqueous phase. The upper end of the range of calculated PFAS Henry"s Law Constants spans the range of most volatile organic compounds of concern for the vapor intrusion pathway. To identify compounds most likely to yield air concentrations that may pose an inhalation concern, Geosyntec compared the theoretical maximum vapor concentrations to estimated levels of potential concern (LOPC) calculated using available USEPA, ATSDR, and state-promulgated toxicological criteria. Consideration of absorption efficiency, distribution in the body, metabolism, and potential for portal-of-entry effects are discussed to support route-to-route extrapolation in derivation of provisional inhalation toxicity criteria to advance these comparisons, predicated on default USEPA-promulgated intake parameter values.

Results suggest that several PFAS compounds may have the capacity to be present in ambient/indoor air at levels that may result in doses above provisional LOPCs. A preliminary review of published literature on PFAS compounds measured in indoor air found that several of the compounds with the highest potential to exceed Geosyntec"s estimated LOPCs were frequently reported as detected in indoor air. These results may be useful for targeting which PFAS compounds to focus on when investigating potential inhalation risks from exposures due to environmental releases of PFAS compounds.

Publication Summary

  • Geosyntec Authors: Travis Kline
  • All Authors: Travis Kline
  • Title: The Association for Environmental Health and Sciences (AEHS) Foundations' 30th Annual International Conference on Soil, Water, Energy, and Air
  • Event or Publication: Event
  • Practice Areas: Per- and Polyfluoroalkyl Substances (PFAS)
  • Citation: Geosyntec practitioners will present at the Association for Environmental Health and Sciences (AEHS) Foundations' 30th Annual International Conference on Soil, Water, Energy, and Air on March 16-19, 2020. The conference will be held at the DoubleTree Mission Valley in San Diego, California.
  • Date: March 16-19, 2020
  • Location: San Diego, California
  • Publication Type: Platform Presentation